Buggy code:
private Object data_remove ( int position ) { } public Component ( final String id ) { } public Component ( final String id , final IModel model ) { } public Component add ( final IBehavior behavior ) { } private void addBehavior ( final IBehavior behavior ) { } private List getBehaviorsImpl ( ) { } public final void afterRender ( ) { } private final void internalBeforeRender ( ) { } private static final MetaDataKey FEEDBACK_LIST = new MetaDataKey ( List . class ) { private static final long serialVersionUID = 1L ; } ; public final void beforeRender ( ) { } public final boolean continueToOriginalDestination ( ) { } public final void debug ( final String message ) { } public final void detach ( ) { } public final void detachBehaviors ( ) { } public void detachModels ( ) { } public final void error ( final Serializable message ) { } public final void fatal ( final String message ) { } public final MarkupContainer findParent ( final Class c ) { } public final MarkupContainer findParentWithAssociatedMarkup ( ) { } public final Application getApplication ( ) { } public final List getBehaviors ( ) { } public final String getClassRelativePath ( ) { } public final IComponentBorder getComponentBorder ( ) { } public final IConverter getConverter ( ) { } public IConverter getConverter ( Class type ) { } public final boolean getEscapeModelStrings ( ) { } public final FeedbackMessage getFeedbackMessage ( ) { } public String getId ( ) { } public final IModel getInnermostModel ( ) { } public Locale getLocale ( ) { } public final Localizer getLocalizer ( ) { } public final ValueMap getMarkupAttributes ( ) { } final Object getMarkupIdImpl ( ) { } private final int nextAutoIndex ( ) { } public String getMarkupId ( boolean createIfDoesNotExist ) { } public String getMarkupId ( ) { } public final Serializable getMetaData ( final MetaDataKey key ) { } private MetaDataEntry [ ] getMetaData ( ) { } public final IModel getModel ( ) { } public final Object getModelObject ( ) { } public final String getModelObjectAsString ( ) { } public final String getModelObjectAsString ( final Object modelObject ) { } public final boolean getOutputMarkupId ( ) { } public final boolean getOutputMarkupPlaceholderTag ( ) { } public final Page getPage ( ) { } public final IPageFactory getPageFactory ( ) { } public final String getPageRelativePath ( ) { } public final MarkupContainer getParent ( ) { } public final String getPath ( ) { } public final boolean getRenderBodyOnly ( ) { } public final Request getRequest ( ) { } public final RequestCycle getRequestCycle ( ) { } public final Response getResponse ( ) { } public Session getSession ( ) { } public long getSizeInBytes ( ) { } public final String getString ( final String key ) { } public final String getString ( final String key , final IModel model ) { } public final String getString ( final String key , final IModel model , final String defaultValue ) { } public final String getStyle ( ) { } public String getVariation ( ) { } public final boolean hasBeenRendered ( ) { } public final boolean hasErrorMessage ( ) { } public final boolean hasFeedbackMessage ( ) { } public final void info ( final String message ) { } public final void internalAttach ( ) { } public final void internalDetach ( ) { } public final boolean isActionAuthorized ( Action action ) { } public final boolean isAncestorOf ( final Component component ) { } public final boolean isEnableAllowed ( ) { } public boolean isEnabled ( ) { } public final boolean isRenderAllowed ( ) { } public final boolean isStateless ( ) { } public boolean isVersioned ( ) { <START_BUG> if ( ( ! ( getFlag ( Component . FLAG_VERSIONED ) ) ) || ( ! ( getFlag ( Component . FLAG_HAS_BEEN_RENDERED ) ) ) ) { <END_BUG> return false ; } else { if ( ( parent ) != null ) { if ( ! ( parent . isVersioned ( ) ) ) { return false ; } } return true ; } } public boolean isVisible ( ) { } public final boolean isVisibleInHierarchy ( ) { } public final void markRendering ( ) { } public final void modelChanged ( ) { } public final void modelChanging ( ) { } public final Page newPage ( final Class c ) { } public final Page newPage ( final Class c , final PageParameters parameters ) { } public void prepareForRender ( ) { } public final void redirectToInterceptPage ( final Page page ) { } public final void remove ( ) { } public Component remove ( final IBehavior behavior ) { } private boolean removeBehavior ( final IBehavior behavior ) { } public final void render ( ) { } public final void render ( final MarkupStream markupStream ) { } public final void renderComponent ( ) { } public final void renderComponent ( final MarkupStream markupStream ) { } public final void rendered ( ) { } public void renderHead ( final HtmlHeaderContainer container ) { } public void replaceWith ( Component replacement ) { } public final boolean sameInnermostModel ( final Component component ) { } public final boolean sameInnermostModel ( final IModel model ) { } public final Component setComponentBorder ( final IComponentBorder border ) { } public final Component setEnabled ( final boolean enabled ) { } public final Component setEscapeModelStrings ( final boolean escapeMarkup ) { } final void setMarkupIdImpl ( Object markupId ) { } public void setMarkupId ( String markupId ) { } public final void setMetaData ( final MetaDataKey key , final Serializable object ) { } public Component setModel ( final IModel model ) { } IModel getModelImpl ( ) { }

Fix:
if ( ! ( getFlag ( Component . FLAG_VERSIONED ) ) ) {